It is becoming apparent that the major obstacles to the successful use of individual nutritional compounds as preventive or therapeutic agents are their efficacy and bioavailability. Traditionally, nutritional compounds in "folk medicine" are used in an unmodified form, as concentrated extracts. Given the fact that the human diet consists of multiple nutrients, it is likely that nutrients in the diet act synergistically to provide health benefits. The concept that food components act in synergism is not new. Centuries ago Hippocrates, the father of medicine, stated "Let food be thy medicine, and let thy medicine be food." Based on this rationale we propose to investigate the synergistic effects of two dietary components: docosahexaenoic acid (DHA) and curcumin (CCM). Our recent studies demonstrate that DHA induced apoptosis in breast cancer cells via enhanced expression of a key cell cycle regulator, p21. Data from other laboratories indicate that CCM also induces p21 expression. Expression of p21 is regulated upstream through multiple mechanisms, including ceramide, peroxisome proliferator-activated receptor-gamma (PPAR?), and p53-mediated pathways. It is apparent that these mediators can be regulated by DHA and/or CCM through common and divergent pathways that may cause a synergistic effect on p21 expression. Our central hypothesis is that DHA and CCM initiate common and divergent cellular pathways that synergistically induce apoptosis by regulating p21 expression. We will test our hypothesis using two specific aims: Specific Aim 1: Determine the synergistic effect of DHA and CCM on breast cancer cells. We will test combinations of DHA and CCM to characterize their apoptotic effects in different breast cancer cell lines. We will investigate common (ceramide formation) and divergent (PPAR? and p53 activation/expression) pathways for their synergistic effects on p21 expression. Specific Aim 2: Determine the preventive/therapeutic effects of DHA and CCM in a breast cancer model. We anticipate that combined treatment with DHA and CCM will be more effective than treatment with DHA or CCM alone in preventing breast cancer development. We will use breast cancer xenograft and carcinogen-induced breast cancer models to further confirm the common (ceramide) and divergent (PPAR? and/or p53) signaling pathways on the synergistic induction of p21 expression by DHA and CCM. The proposed investigation is innovative because the synergy of DHA and CCM has never been studied in any cancer model. Our studies are significant because the study outcome will lead to further investigation to determine whether combinations of nutrients provide synergistic effects to prevent breast cancer to those at a high risk of developing cancer as well as to prevent the recurrence or spread to other tissues after initial chemotherapy. We anticipate that the results of this study will help us develop an expanded research project for a future R01 grant application. Based on these studies, we will propose studies on different cancer models for the prevention, treatment, and reoccurrence of tumors using combinations of other nutritional compounds.